Conical cornea is a disease that a corneal parenchymal layer thins and a central region protrudes. Its reason is not yet understood and there is currently no treatment method other than suppression of the protrusion with a contact lens or transplantation of cornea.
In a study for treatment of conical cornea, there is reported a method of crosslinking collagen in the corneal parenchymal layer by adding riboflavin (vitamin B2) dropwise into the eye and irradiating the eye with ultraviolet ray (for example, Non-patent Document 1). However, it is difficult to stop progress of conical cornea completely and the damage due to UV irradiation also causes a problem.
Crosslinking agents that crosslink collagen by chemical bondings are known. For example, known in Japan are a photoreactive gelatin-polyethylene glycol (PEG) diacrylate crosslinking agent, developed by Matsuda et al. (Non-patent Document 2), a succinimidated citric acid crosslinking agents, developed by Taguchi et al. (Non-patent Document 3) and an aldehyde group-containing polymeric micelle crosslinking agent, developed by Murakami et al. (Non-patent Document 4); and known abroad are succinimidated PEGs, developed by Wallance et al. (Non-patent Document 5) and others. However, there is concern about toxicity by residual monomers and unreacted functional groups and there is also a problem of stability.
Patent Document
[Non-patent Document 1] T. Seiler et al., Am. J. Ophthalmol., 135, 620 (2003)
[Non-patent Document 2] J. Biomed. Mater. Res. 1999
[Non-patent Document 3] Mater. Sci. Eng. C2004
[Non-patent Document 4] J. Biomed. Mater. Res. 2007
[Non-patent Document 5] J. Biomed. Mater. Res. 2001